文档介绍：Fertilizers and Environmental
Chapter 9
The principles of application fertilizers
Law of the Minimum:the crop’s yield is restricted by the lack of one element, even though there may be sufficient quantities of all the other elements.
Law of Diminishing Return
报酬递减律
the response of a plant to the addition of a growth will e smaller and smaller as the amount of the growth factor increases
The principles of application fertilizers
Yield or growth cure
Fertilizer use and agricultural production
Year
Number of people supported by one hectare
Grain yield per hectare
Fertilizer consumption
kg NPK per hectare
1800
-
1875
1900
1925
1950
1975
1978
The major factors that control crop quality are ically controlled, but environmental and nutritional factors do have some influence.
Crop Quality and application fertilizer
80 kg N/ha
+40 kg N/ha at flowering stage
+60 kg N/ha at flowering stage
Yield (tonnes/ha)
Protein content %
Sedimentation value
The additions of N at flowering increased grain yield and baking quality. This may not be true in dry areas.
Crop Quality and application fertilizer
In potatoes, K increases the translocation of carbohydrates from the leaves to the tubers resulting in an increase in the starch content of potatoes.
K also increases the content of citric acid which reduces the occurrence of black spot in potatoes.
Crop Quality and application fertilizer
The quality of oil crops may be affected by N nutrition. The oil content of canola seeds was reduced by high levels of N.
Nitrogen rate
Seed yield (g/pot)
Seed wt (mg/seed)
Oil content % DM
Low
High
Crop Quality and application fertilizer
Vegetable and Fruit Quality
NO3- NO2- during storage and processing of fruits and vegetables
NO3- NO2- in the stomach
NO2-